It has long been known to display astronomical temporal magnitudes such as the phases of the moon, the evolution of the sun and of the planets in the planisphere and in relation to the ring of the Zodiac signs, the eclipses of the sun and of the moon, etc. Horological mechanisms have been designed, e.g. for use in monuments and in astrolabes of smaller size, that can be accommodated on a table.
But the designing of astrolabes of wrist-watch size has always run into considerable difficulties, since the reduced dimensions and the need for sturdiness and reliability in such timepieces is difficult to reconcile with the complexity and the degree of precision that are expected of an astrolabe operating in a satisfactory manner and displaying the astronomical magnitudes with the required accuracy.